Method of preserving cooked potatoes

ABSTRACT

Peeled, cooked, and cut fresh potatoes are preserved in a sealed refrigerated container filled with a mixture of carbon dioxide and nitrogen.

United States Patent 11 1 Nov. 20, 1973 Ruggerone [54] METHOD OFPRESERVING COOKED [56] References Cited POTATOES UNITED STATES PATENTS[75] Inventor: Artemio P. Ruggerone, Covina, 2,490,951 12/1949 Dunkley99/189 m R14,489 6/1918 Franks 99/189 x 2,114,622 4/1938 Bergstein...99/171 S X Asslgneer Lloyd Shapoff, Hawthorne, Cahf- 2,838,403 6/1958Notter 99/187 x 3,102,778 9/1963 Bedrosian et a1. 99/189 x [22] July1970 3,220,857 11/1965 Hollis, Jr. et al. 99 207 [21] Appl, 64,1193,360,382 12 1967 Miller 99/189 x 3,393,077 7/1968 Moreau 99/189 xRelated Appllcaflon Data 3,449,134 6 1969 Leasure et a1. 99/189Continuation of Ser. No. 703,1841, Jan. 14, 1968, abandoned,Continuation-impart of Ser. No. 657,903, Aug. 2, 1967, abandoned.

US. Cl. 426/106, 99/100 P, 99/189,

99/467, 426/205, 426/227 Int. Cl. A23b 7/14, 1365b 31/00 Field of Search99/189, 171, 171 S,

Primary ExaminerNorman Yudkoff Assistant ExaminerKenneth P. Van WyckAttorney-Cristie, Parker & Hale [5 7] ABSTRACT Peeled, cooked, and cutfresh potatoes are preserved in a sealed refrigerated container filledwith a mixture of carbon dioxide and nitrogen.

7 Claims, 2 Drawing Figures METHOD OF PRESERVING COOKED POTATOES Thisinvention relates to extending the shelf life of peeled, cooked, and cutpotatoes, and is a continuation of Ser. No. 703,841 filed Jan. 19, 1968,now abandoned which is a continuation-in-part application of mycopending US. Pat. application Ser. No. 657,903, filed Aug. 2, 1967, nowabandoned.

Widespread use of pre-peeled and pre-cooked potatoes in consumer packs,particularly in retail merchandising, has been inhibited by difficultiesin keeping the product in good condition for the required length of timefrom the processing plant to the ultimate consumer.

This invention provides method and apparatus for extending the shelflife of pre-peeled and pre-cooked potatoes. Such potatoes are normallycut or shredded and sold as instant french fries or hash brown potatoes.In accordance with this invention, potatoes, which have been pre-peeledand pre-cooked, are placed in a package which contains a mixture ofcarbon dioxide and nitrogen gas and which is sealed to keep the gasmixture in the container. Preferably, the sealed container with thepotatoes in it is made of an airimpervious material, such as polyvinylchloride, and is stored at a temperature between about 34 F and about 55F. Moreover, the gas mixture is preferably flushed through the packageprior to sealing to displace ambient air from the product. This is mostconveniently accomplished by injecting the gas mixture under positivepressure at one end of the package, and withdrawing air or gas through avacuum tube at the opposite end of the package. Ordinarily, a smallpercentage of oxygen originally present in the ambient air in thepackage is left in the package to inhibit botulism.

The invention will be more fully understood from the following detaileddescription, and the accompanying drawings, in which:

FIG. 1 is a perspective view of the package prior to sealing; and

FIG. 2 is a cross sectional view of the package after sealing.

Raw potatoes (not shown), preferably those with a high solid content andrelatively small in size, i.e., under 6 ounces per potato, are peeledand trimmed, and cooked between about 200 and about 212 F for aboutminutes. The cooking time and temperature are adjusted so that thepotatoes are cooked down all the way through. This is most easilydetermined by piercing the cooked potatoes with a fork or the like,which should slip easily into a properly cooked potato. lf occasionallarge potatoes are undercooked, they are cut in half during the trimmingoperation.

After cooking, the potatoes are dipped in a conventional preservativeand allowed to cool to room temperature. This normally requires about 4hours. The cooled potatoes are then placed in a refrigerated room andheld there for at least 24 hours, and preferably 48 hours. Therefrigerated room is preferably held at about 35 F, and about 50 percentmaximum relative humidity. After such treatment, cooked potatoes have amoisture content in the range of about 70 percent to 85 percent byweight.

After storage in the refrigerated room, the cooled'potatoes are shreddedif they are to be hash browns" or they are cut into conventional finger"shapes if they are to be french fries."

The cut or shredded potatoes 10 are placed in a container 11 which isimpervious to oxygen. Preferably, the container is rectangular, open atits top, and has an outwardly extending sealing flange 12 around itsperiphery. The container is also perferably made of a material, such aspolyvinyl chloride, which is impervious to air. A rectangular lid 13with a periphery matching that of the sealing flange is temporarilydeformed to curve concave downwardly about an axis which is generallyparallel to thelongitudinal axis of the container. The lid and thecontainer are each made with sufficient structural strength to beself-supporting, i.e., retain a fixed shape when standing alone.

With the lid resting loosely on the sealing flange so the container isopen at each end, a mixture of carbon dioxide and nitrogen gas isinjected into one end of the container. The gas mixture is heavier thanthe ambient air, and therefore settles to the bottom of the container,displacing the air until the container is filled with carbon dioxide andnitrogen. To speed the displace-ment of the air with the gas mixture,air is withdrawn from the opposite end of the package where the carbondioxide and nitrogen gas is injected. Preferably, a head space is leftbetween the top of the potatoes in the package and the package flange toinsure that a trace of oxygen is left in the package to inhibitbotulism. For example, for a package which is about 5 inches long, 4-%inches wide, and about l-r inches deep, a head space of about one-fourthinch is adequate. Ordinarily, between about 1 percent and about 5percent oxygen remaining in the package is adequate to produce thedesired inhibition. If too much oxygen is left in the package, anyaerobic bacteria which may be present could grow and thus reduce theshelf life of the product. Thereafter, the lid is hermetically sealed tothe container around the entire periphery of the lip to form anair-tight package. The lid is also made of an airimpervious material.

Preferably, the mixture injected into the container is between about 30percent and about percent carbon dioxide, with the balance beingnitrogen. Maximum shelflife has been obtained when the mixture is 50percent carbon dioxide and 50 percent nitrogen for shredded hash brownpotatoes, and 70 percent carbon dioxide and 30 percent nitrogen forfrench fried potatoes.

After the container is flushed with the mixture of carbon dioxide andnitrogen gas to displace ambient atmosphere, and the lid sealed to thecontainer, the package is stored at a temperature between about 34 F andabout 55 F.

The mixture of carbon dioxide and nitrogen produces a product superiorto that obtained when either pure nitrogen or pure carbon dioxideisused-alone. For example, if pure carbon dioxide is used, the shelflife is relatively short (about one week) and there is a tendency for anexcessive amount of moisture to be present in the container. Moreover,when the gas mixture is substantially percent carbon dioxide, anexcessive volume of gas is absorbed by the product, resulting in areduced pressure within the container, which eventually is distorted,thereby interfering with its merchandising appeal. If the concentrationof the carbon dioxide is reduced much below about 30 percent, thereliable shelf life of the product is not much greater than about oneweek.

A mixture of gas in the range of about 30 percent to about 70 percentcarbon dioxide, with a balance being nitrogen, provides a shelf life ofup to sixteen weeks, with best results being obtained when the mixtureis 50 percent CO and 50 percent nitrogen.

What is claimed is:

l. A package of food adapted for storage at temperatures between about34 F. and about 55 F. comprising a container of air-impervious material,potatoes peeled and cooked to a moisture content in the range of fromabout 70 percent to 85 percent by weight disposed in the container, amixture of carbon dioxide and nitrogen gas in the container around thepotatoes, the carbon dioxide in the gas mixture being present in theamount between about 30 percent and about 70 percent by volume with thebalance being substantially nitrogen, and means sealing the container toprevent the gas mixture from being removed from the container or dilutedby gas outside the container.

2. A package according to claim 1 in which the container is made of aself-supporting material.

3. A method for preserving potatoes, peeled and cooked to a moisturecontent of from about 70 percent to 85 percent by weight for storage attemperatures between about 34 F. and about 55 F., the method includingthe steps of disposing the potatoes in an airimpervious container,displacing air from the container which the carbon dioxide is present inthe amount between about 30 percent and about percent by volume with thebalance being substantially nitrogen, and sealing the container toconfine the gas mixture therein so that the gas mixture is preventedfrom being removed from the container or diluted by gas outside thecontainer.

4. A method according to claim 3 in which the carbon dioxide andnitrogen gas are present in substantially equal amounts.

5. A method according to claim 3 which includes the step ofrefrigerating the sealed container between about 34 F and about 55 F.

6. A method according to claim 3 wherein the carbon dioxide is presentin an amount of about 70 percent by volume, the balance being nitrogen.

7. A method according to claim 3 and including the steps of disposingthe potatoes in a container open at its top, placing a lid loosely ontop of the container, injecting the gas mixture of carbon dioxide andnitrogen at one point of the container to drive air from the containerat another point, and sealing the lid to the container to make ahermetically sealed package.

2. A package according to claim 1 in which the container is made of aself-supporting material.
 3. A method for preserving potatoes, peeledand cooked to a moisture content of from about 70 percent to 85 percentby weight for storage at temperatures between about 34* F. and about 55*F., the method including the steps of disposing the potatoes in anair-impervious container, displacing air from the container with amixture of carbon dioxide and nitrogen gas in which the carbon dioxideis present in the amount between about 30 percent and about 70 percentby volume with the balance being substantially nitrogen, and sealing thecontainer to confine the gas mixture therein so that the gas mixture isprevented from being removed from the container or diluted by gasoutside the container.
 4. A method according to claim 3 in which thecarbon dioxide and nitrogen gas are present in substantially equalamounts.
 5. A method according to claim 3 which includes the step ofrefrigerating the sealed container between about 34* F and about 55* F.6. A method according to claim 3 wherein the carbon dioxide is presentin an amount of about 70 percent by volume, the balance being nitrogen.7. A method according to claim 3 and including the steps of disposingthe potatoes in a container open at its top, placing a lid loosely ontop of the container, injecting the gas mixture of carbon dioxide andnitrogen at one point of the container to drive air from the containerat another point, and sealing the lid to the container to make ahermetically sealed package.